TW201306423A - Non-contact power feeding system - Google Patents

Abstract

A non-contact power supply system comprises: a power supply device which includes a plurality of primary coils which are excited with an operating frequency (f1); and a power receiving device which includes a secondary coil which induces a current on the basis of alternating magnetic fluxes from the primary coils. The operating frequency (f1) which excites the primary coils is set to either a resonant frequency (fb2) or near thereto (fx-fy) of a resonance assembly which is formed when the secondary coil is present in a staggered location between two adjacent primary coils.

Description

Contactless power supply system

The present invention relates to a contactless power supply system that supplies power to a power receiving device in a non-contact manner.

In the past, there has been a non-contact power supply system in which a power receiving device supplies power to a power receiving device in a non-contact manner (see, for example, Patent Document 1). In the conventional non-contact power supply system, when power is supplied, the power receiving device is placed at a fixed position in the power supply device. Only in this state, the power receiving device can be powered by the power supply device.

In recent years, in order to further improve the convenience of users, some people have reviewed the so-called free-laying type non-contact power supply system, and the power receiving device can be powered only by setting the power receiving device at any position on the upper surface (power supply surface) of the power supply device ( Refer to, for example, Patent Document 2).

As shown in FIG. 5(a), in the free-layout type non-contact power supply system, a plurality of coils L1 are arranged along the power supply surface 6 inside the power supply device 10. Further, the power receiving device 30 is provided with the secondary coil L2. In Fig. 5(a), the secondary coil L2 is in the state of the primary coil L1. This primary coil L1 is excited by the operating frequency f1. In the secondary coil L2, a current is induced by a change in the magnetic flux from the primary coil L1 that is excited. This induction produces an output current of the power receiving device 30. In this manner, the power receiving device 30 is supplied with electric power by the electromagnetic induction self-power supply device 10.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-204637

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-5573

In the conventional non-contact power supply system (non-free layout system), as shown in FIG. 7, the operating frequency f1 of the primary coil L1 is set, and the resonant frequency in the resonant system when the secondary coil L2 is aligned with the secondary coil L1. Fr is consistent. This resonance frequency fr is the resonance frequency of the secondary coil L2. In the conventional non-contact power supply system, since the power receiving device is disposed at a position fixed to the power supply device, the secondary coil L2 can be aligned with the primary coil L1 during power supply. Therefore, the operating frequency f1 can be made the resonance frequency fr, whereby the maximum output power W1 is obtained by the power receiving device 30.

On the other hand, in the above-described free-layout type non-contact power supply system, it is not necessary to particularly provide the power receiving device 30 at a fixed position on the power supply surface 6. Therefore, as shown in FIG. 5(b), the secondary coil L2 may be placed at a gap position between the two primary coils L1. When the secondary coil L2 is aligned with the position of the primary coil L1, the leakage inductance Le is the smallest. Further, as the secondary coil L2 is displaced from the alignment position along the power supply surface 6, the leakage inductance Le increases.

It is known that the larger the leakage inductance Le is, the smaller the resonance frequency fr is. Therefore, as indicated by the arrow in Fig. 7, the resonance frequency fr in the resonance system decreases as the position of the secondary coil L2 with respect to the primary coil L12 deviates. Therefore, when the primary coil L1 is in the gap position, the output power W2 is significantly lower than the output power W1 when the output power W1 is in the aligned position. In the free-layout type non-contact power supply system, the position of the power receiving device 30 is different from the output power of the power receiving device 30, and it is difficult to ensure stable output power.

In view of the circumstances, it is an object of the present invention to provide a non-contact power supply system in which stable output power can be obtained regardless of the position of the secondary coil.

A non-contact power supply system according to an aspect of the present invention includes: a power supply device having a plurality of times of oscillating at an operating frequency along a power supply surface The coil and the power receiving device have a secondary coil that induces a current due to an alternating magnetic flux from the primary coil in a state of being disposed on the power feeding surface.

The non-contact power supply system is characterized in that the operating frequency of the primary coil excitation is set to a resonance frequency of a resonance system formed when the secondary coil exists at a gap position between two adjacent primary coils adjacent to each other. Or nearby.

In the above configuration, the contactless power supply system may have a capacitor that connects the secondary coils.

In this configuration, it is preferable to set the operating frequency to the resonance frequency of the resonance system corresponding to the gap position or the vicinity thereof by adjusting the capacitance of the capacitor.

Further, in the above configuration, it is preferable that the vicinity of the resonance frequency is a resonance system formed when the power output of the power receiving device obtained by the resonance system corresponding to the gap position is present in the primary coil at the position where the secondary coil is aligned. The frequency region in which the power receiving device outputs power is obtained.

In the above configuration, it is preferable to set the operating frequency so as not to coincide with the same resonance frequency in the vicinity of the resonance frequency in the resonance system at the gap position.

Hereinafter, an embodiment of the non-contact power supply system will be described with reference to Figs. 1 to 6 .

As shown in FIG. 1, the contactless power supply system includes a power supply device 10 and a power receiving device 30. In this example, the power receiving device 30 is built in the mobile terminal unit 40. The specific configuration of the power supply device 10 and the power receiving device 30 will be described below.

(power supply device)

As shown in FIG. 2, the power supply device 10 includes a flat frame 5. A power supply surface 6 on which the mobile terminal 40 is placed is formed on the upper surface of the casing 5. Inside the casing 5, a plurality of coils L1 are arranged in all areas across the power supply surface 6. In this example, the 24 primary coils L1 are arranged in a matrix of 4 rows×6 columns on the feeding surface 6.

As shown in FIG. 1, the power supply device 10 includes a single common unit 11 and a plurality of power supply units 15 (the same number of 24 coils as the primary coil L1 in this example) connected to the common unit 11.

The common unit 11 includes a power supply circuit 13 and a common control circuit 12. The power supply circuit 13 converts the AC power from the external power source into an appropriate DC voltage, and the DC voltage is supplied to the power supply unit 15 and the common unit 11 as the operating power.

The common control circuit 12 is constituted by a microcomputer, and the power supply device 10 is integrated and controlled by supplying various command signals to the respective power supply units 15.

The power supply unit 15 includes a unit control circuit 19, an excitation drive circuit 16, and a primary coil L1.

The unit control circuit 19 receives the command signal from the common control circuit 12 for requesting power supply, that is, performs control of the excitation drive circuit 16.

The excitation drive circuit 16 is connected to both ends of the primary coil L1. Further, a capacitor C1 is connected between one end of the primary coil L1 and the excitation drive circuit 16. The excitation drive circuit 16 is controlled by the unit control circuit 19 to generate an alternating current of the operation frequency f1, and is supplied to the primary coil L1 and the capacitor C1. Thereby, the primary coil L1 is excited. At this time, the magnetic flux generated from the primary coil L1 changes.

(power receiving device)

As shown in FIG. 1, the power receiving device 30 includes a rectifier circuit 31 and a DC/DC converter. 35.

The rectifier circuit 31 is connected to both ends of the secondary coil L2. Further, a capacitor C2 is connected between one end of the secondary coil L2 and the rectifier circuit 31. The secondary coil L2 induces a current due to a change in the magnetic flux from the primary coil L1. The rectifier circuit 31 rectifies the alternating current induced by the secondary coil L2. The DC/DC converter 35 converts the DC voltage from the rectifier circuit 31 into a value suitable for the operation of the mobile terminal 40. This DC voltage is used to charge, for example, the secondary battery (not shown) that operates the power supply of the mobile terminal 40.

Next, the resonance characteristics in the non-contact power supply system will be explained.

Fig. 3 is a graph showing a resonance system showing the output power of the power receiving device 30 corresponding to the primary coil L1 operating frequency. As shown in FIG. 3, in the resonance system of the present embodiment, there are two resonance frequencies of the primary side resonance frequency fa1 and the secondary side resonance frequency fb1. The primary side resonance frequency fa1 is lower than the secondary side resonance frequency fb1. These resonance frequencies fa1 and fb1 are resonance frequencies when the secondary coil L2 is at the position of the positive primary coil L1.

When the operating frequency f1 at which the primary coil L1 is excited is set to the primary side resonance frequency fa1, the impedance of the two coils L1 and L2 is excessively lowered in the state of magnetic coupling, and the circuit efficiency is lowered. Therefore, in this example, the operating frequency f1 at which the primary coil L1 is excited is set to be near the secondary side resonance frequency fb1 by the secondary side resonance frequency fb1. By setting the operating frequency f1 near the secondary side resonance frequency fb1, the impedance is excessively lowered. The resonance frequency is derived from the following equation.

According to the equation (1), the smaller the leakage inductance Le or the capacitance C of the capacitor, the smaller the resonance frequency. For example, the position of the secondary coil L2 from the aligned primary coil L1 shown in Fig. 5(a) When it is deviated in the direction of the surface of the power supply surface 6, the deviation Le leakage inductance Le increases. At this time, the resonance system (resonance curve) shown by the solid line in FIG. 3 moves in the direction in which the resonance frequency decreases (the left direction in FIG. 3). Further, as shown in FIG. 5(b), when the secondary coil L2 exists at a gap position between the two primary coils L1 adjacent to each other, the resonance system (resonance curve) is set as shown by a broken line in FIG. The frequency. As described above, the primary side resonance frequency fa2 and the secondary side resonance frequency fb2 at the gap position are respectively smaller than the secondary side resonance frequency fa1 and the secondary side resonance frequency fb2 at the alignment position.

Further, as shown in the above formula (1), by adjusting the capacitance C of the capacitor C2, the resonance frequency (frequency region of the resonance system) with respect to the operation frequency f1 can be set. At this time, the operating frequency f1 can be fixed.

Figure 4 is an enlarged view showing the range A of Figure 3. As shown in FIG. 4, as in the prior art described above, when the operating frequency f1 is set to the resonant frequency fb1 of the aligned position, the difference between the output power of the power receiving device 30 at the gap position and the output power of the power receiving device 30 at the aligned position is Δ. W1 is the largest. At this time, as shown in the graph of Fig. 6(a), the output power of the power receiving device 30 at the aligned position is maximum (about 50 W). Further, when the secondary coil L2 is present at the intermediate position between the alignment position and the gap position, the output power of the power receiving device 30 is less than 20 W. When the secondary coil L2 is present at the gap position, the output power of the power receiving device 30 is about 10 W. Therefore, when the operating frequency f1 is set to the resonance frequency fb1 of the aligned position, the output power when the secondary coil L2 is at the gap position is reduced to about 20% of the output power of the aligned position.

On the other hand, in the present embodiment, the position of the resonance system with respect to the operation frequency f1 is set by adjusting the capacitance C of the capacitor C2, and the output power of the power receiving device 30 at the gap position and the output power of the power receiving device 30 at the aligned position are used. The difference is small. In this example, the operating frequency f1 is set to be near the resonance frequency fb2 at the gap position. As shown in FIG. 4, the vicinity of the resonance frequency fb2 is a resonance system (resonance curve indicated by a broken line) corresponding to the gap position, and two resonance points fx of the resonance system (resonance curve indicated by a solid line) corresponding to the alignment position. The frequency area between fy and fy. That is, setting the resonance of this embodiment Therefore, the operation frequency f1 is located between two intersections fx and fy. When the operating frequency f1 is set between the two intersections fx and fy, the output power at the gap position is equal to or higher than the output power at the aligned position.

When the operating frequency f1 is set near the resonance frequency fb2, the difference ΔW2 between the output power of the power receiving device 30 at the gap position and the output power of the power receiving device 30 at the aligned position is smaller than the difference ΔW1. At this time, as shown in the graph of Fig. 6(b), the output power of the power receiving device 30 at the gap position is the largest (about 40 W). Further, when the secondary coil L2 is present at the intermediate position between the alignment position and the gap position, the output power of the power receiving device 30 is approximately 30 W. When the secondary coil L2 is present at the aligned position, the output power of the power receiving device 30 is approximately 20 W. Therefore, in the present configuration, the reduction ratio of the output power to the positive position with respect to the gap position is only about 50%. Therefore, regardless of the position of the secondary coil L2, the output power of the power receiving device 30 can be obtained more stably.

The contactless power supply system of this embodiment has the following advantages.

(1) The operating frequency f1 is set to be near the resonance frequency fb2 at the gap position. Thereby, the output power difference of the power receiving device 30 between the gap position and the alignment position can be reduced as compared with, for example, when the set operating frequency f1 is the resonance frequency fb1 at the aligned position. Therefore, regardless of the position of the secondary coil L2, a more stable output power of the power receiving device 30 can be obtained.

(2) The position of the resonance system with respect to the operating frequency f1 is set by adjusting the capacitance C of the capacitor C2. Thereby, even if, for example, the operation frequency f1 is determined in advance according to specifications or the like, the operation frequency f1 can be fixed to the value according to the specification, and at the same time, the output power of the power receiving device 30 can be more stably obtained.

(3) The operating frequency f1 is set and does not coincide with the resonance frequency fb2 at the gap position. Here, when the operation frequency f1 coincides with the resonance frequency fb2 at the gap position, the output power difference of the power receiving device 30 increases because the operating frequency f1 does not match the resonance frequency fb1 at the alignment position. Therefore, by making the operating frequency f1 The output power difference of the power receiving device 30 can be further reduced without being coincident with the resonance frequency fb2 at the gap position.

Further, the above embodiment can be implemented in the following modes as appropriate.

In the above embodiment, the position of the resonance system with respect to the operating frequency f1 is set by adjusting the capacitance C of the capacitor C2. However, it is also possible to set the operating frequency f1 near the resonance frequency fb2 at the gap position by changing the operating frequency f1.

In the above embodiment, the vicinity of the resonance frequency fb2 is a frequency region between the resonance curve of the gap position and the two intersections fx and fy of the resonance curve corresponding to the alignment position. Further, the operating frequency f1 is set between the intersections fx and fy. However, as long as the output power difference of the power receiving device 30 between the gap position and the alignment position is small compared to the set operating frequency f1 at the resonance frequency fb1, the frequency region in which the operating frequency f1 is set is not limited thereto. For example, the operating frequency f1 may be set in a frequency region smaller than the intersection fx, or the operating frequency f1 may be set in a frequency region larger than the intersection fy. That is, it means that the frequency region near the resonance frequency fb2 can have a wider range.

‧ The resonance system can also be set at a position where the operating frequency f1 coincides with the resonance frequency fb2 at the gap position. At this time, stable output power can be obtained as compared with the case where the set operating frequency f1 is in the vicinity of the resonance frequency fb1 at the alignment position (particularly, the frequency region higher than the resonance frequency fb1).

‧ The unit control circuit 19 in the above embodiment can also be omitted. At this time, the common control circuit 12 also performs the control performed by the unit control circuit 19 in the above embodiment. The common control circuit 12 can also perform part of the control performed by the unit control circuit 19, and the unit control circuit 19 can also perform part of the control performed by the common control circuit 12.

In the above embodiment, the coil L1 and the capacitor C1 are directly connected but may be connected in parallel. Further, the coil L2 and the capacitor C2 are connected in series but may be connected in parallel.

A‧‧‧Scope

C1, C2‧‧‧ capacitor

C‧‧‧ capacitor

F1‧‧‧ operating frequency

Fa1‧‧‧1 side resonance frequency

Fa2‧‧‧1 side resonance frequency

Fb1‧‧‧2 secondary resonance frequency

Fb2‧‧‧2 secondary resonance frequency

Fr‧‧‧resonance frequency

Fx, fy‧‧‧ intersection

L1‧‧1 times coil

L2‧‧2nd coil

Le‧‧‧ leakage inductance

W1, W2‧‧‧ output power

△W1, △W2‧‧‧ Poor

5‧‧‧ frame

6‧‧‧Power supply surface

10‧‧‧Power supply unit

11‧‧‧Common unit

12‧‧‧Common control circuit

13‧‧‧Power circuit

15‧‧‧Power supply unit

16‧‧‧Excitation drive circuit

19‧‧‧Unit control circuit

30‧‧‧Power-receiving device

31‧‧‧Rectifier circuit

35‧‧‧DC/DC converter

40‧‧‧Mobile terminal

Figure 1 is a block diagram showing the construction of a contactless power supply system.

2 is a perspective view of a power supply device.

Fig. 3 is a graph showing a resonance system including the primary side and the secondary side frequencies.

Figure 4 is an enlarged view of the range A resonance curve of Figure 3.

Fig. 5(a) is a partial cross-sectional view showing the power supply device and the power receiving device when the secondary coil L2 is in the aligned position, and (b) is a partial cross-sectional view showing the power supply device and the power receiving device when the secondary coil L2 is in the gap position.

Fig. 6(a) is a graph showing the output power of the power receiving device corresponding to the secondary coil L2 position in the conventional resonance system setting, and (b) showing the output power of the power receiving device corresponding to the secondary coil L2 position in the resonance system setting of the present invention. Graph.

Fig. 7 is a graph showing the resonance system of the prior art non-contact power supply system in which the resonant system and the secondary coil are in the gap position when the secondary coil is in the aligned position.

F1‧‧‧ operating frequency

Fb1‧‧‧2 secondary resonance frequency

Fb2‧‧‧2 secondary resonance frequency

Fx, fy‧‧‧ intersection

△W1, △W2‧‧‧ Poor

Claims (4)

A non-contact power supply system comprising: a power supply device having a plurality of primary coils arranged along a power supply surface and excited by an operating frequency; and a power receiving device having a state of being disposed on the power supply surface due to the primary coil a secondary coil that induces a current by alternating magnetic flux; and a resonance phenomenon is utilized in the secondary coil; the non-contact power supply system is characterized in that the operating frequency of the primary coil excitation is set to the secondary coils present in each other The resonance frequency of the resonance system formed at or near the gap position between the two adjacent primary coils or its vicinity. The non-contact power supply system of claim 1, wherein the capacitor having the second coil is set, and the operating frequency is set to a resonance frequency of the resonance system corresponding to the gap position by adjusting the capacitance of the capacitor. Or nearby. The non-contact power supply system of claim 1 or 2, wherein the vicinity of the resonance frequency is an output power of the power receiving device obtained by the resonance system corresponding to the gap position in the secondary coil The frequency region of the power receiving device output power obtained by the resonance system formed when the primary coil is aligned. The contactless power supply system of claim 1 or 2, wherein the operating frequency is set to be near the resonant frequency in the resonant system at the gap position, and not coincident with the resonant frequency.